The present invention relates to a data processing apparatus which temporarily stores image data input from an image reading section, such as a scanner, or image data input via a communication circuit, such as a LAN or the Internet, into a memory device, records the stored image data on a recording medium, such as a copy sheet, and sends the image data to outside by facsimile communication or by data communication, and, more particularly, to a data processing apparatus which enhances the security of image data temporarily stored.
There is an image processing apparatus (data processing apparatus) with an electronic filing function which optically scans and reads an original to be copied as image data, temporarily stores the scanned image data into a storage medium, such as a hard disk, and reads out desired image data from the storage medium and prints the image data on a recording sheet according to an instruction (see e.g., Japanese Patent Application Laid-Open No. H6-178041(1994)).
The image processing apparatus with such an electronic filing function manages the storage locations or so on the storage medium at the time of storing image data and the storage locations or so on the storage medium at the time of reading image data according to, for example, a FAT (File Allocation Table). In the FAT, data numbers are allocated to individual pieces of data to be stored in the storage medium, and the storage locations of individual pieces of image data on the storage medium are specified as reference values in the FAT are determined by the data numbers.
The FAT is updated every time image data to be managed is newly stored. For image data whose printing has been done, when management information about the image data is erased from the FAT, FAT-based reading cannot be carried out. Therefore, leakage or so of image data can be prevented by erasing management information about the image data whose printing has been done from the FAT.
Even when management information about the image data whose printing has been done is erased from the FAT, however, the image data stays stored in the storage medium (e.g., a hard disk) unless the data is overwritten with another image data or so. It is therefore possible to remove the storage medium from the image processing apparatus, and read and acquire the image data left stored from the storage medium illegitimately.
In this respect, the following technologies have been proposed in consideration of the security of image data against information leakage or illegitimate usage. For example, the technologies include an image processing apparatus which is permitted to be used when a user is verified (Japanese Patent Application Laid-Open No. H7-28365(1995)), an image processing apparatus which buries specific information in image data to be output so that the route of the image data can be traced (Japanese Patent Application Laid-Open No. 2000-187419), an image processing apparatus which encrypts image data and stores the encrypted image data (Japanese Patent Application Laid-Open No. H1-256068(1989)), and an image processing apparatus which automatically erases image data from a storage medium when the image data becomes unnecessary (Japanese Patent Application Laid-Open No. H9-223061(1997). Those technologies are said to be able to prevent leakage or illegitimate usage of image data remaining in the apparatus.
There is also a data security kit available as a commercial product which prevents leakage or illegitimate usage of image data from an electronic filing function by encrypting or erasing image data stored in a storage medium, such as a hard disk, or erasing image data stored in a memory. Such a data security kit can be adapted to the electronic filing function, and can be installed later in various kinds of apparatus, not to mention an image processing apparatus having an electronic filing function.